You are correct that pref -DMNAME ST0 to display this display manager variable value is safe. It is the pref -DMNAME dmcmd "dmcmds" that can be extremely dangerous, especially while learning display manager commands, or even have a fat finger later. The main danger with using pref is just how flexible and powerful display manager commands are. They can control process just as easily as they can control displays. You can execute a display manger command from any Foxboro computer to any display on any other Foxboro display. The main danger is that while the display executing the command is easily traceable...to my knowledge (although I am not a cyber forensics expert)there is no way to track where the display manager command was issued from originally (who done it). Very bad in today's cyber paranoid world. And there is also the fact that there are usually a lot more DMNAMES than WPs/AWs making it very easy to use the wrong dmname and cause an inappropriate action on another WP/AW. However, pref's ability to control process is the very scariest part. Pref is great and powerful stuff, just maybe too flexible and powerful for today's control environment! Jack Easley Sr. I&C Technician Luminant Power, Martin Lake Plant Phone 903.836.6290 jack.easley@xxxxxxxxxxxx -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Ricardo Abech Sent: Tuesday, December 20, 2011 6:32 AM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] Active Foxview Display Thanks Terry …. I was under the impression that the "pref ST0" or "pref ST1" only collected the actual display and did not execute anything. So you mean that calling the pref is actually recalling the display or affecting it some how? Thanks! On Dec 20, 2011, at 10:26 AM, Terry Doucet wrote: Ricardo,Careful with pref because it can force a FV or DM command to execute. If you use the variable that Bud suggested with an omget or omgetimp you can get the WP to return the name of the existing (or last) display without re-calling the display or executing any other commands. Pref can be dangerous if you execute it while an Operator is using the station where you force the pref to execute. Terry Confidentiality Notice: This email message, including any attachments, contains or may contain confidential information intended only for the addressee. If you are not an intended recipient of this message, be advised that any reading, dissemination, forwarding, printing, copying or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by reply message and delete this email message and any attachments from your system. _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave